CN115094521A - Boron diffusion reaction system and process method thereof - Google Patents

Abstract

The invention provides a boron diffusion reaction system and a process method thereof, wherein a raw material pipeline of the boron diffusion reaction system is connected with an air inlet pipeline, and raw material gas is conveyed into a reaction furnace pipe through the air inlet pipeline; the exhaust pipe is arranged at the furnace tail of the reaction furnace pipe and is positioned at the pipe axis position of the reaction furnace pipe; the air inlet pipelines comprise a first air inlet pipeline and a second air inlet pipeline, air outlets of the first air inlet pipeline and the second air inlet pipeline are positioned at the furnace mouth, and the air outlets of the first air inlet pipeline and the second air inlet pipeline are distributed in the vertical direction of the reaction furnace tube in an up-down symmetrical mode in a split plane. According to the gas supply system combined process method, the boron source pipeline arrangement and the process steps are optimized, the purging steps are carried out for multiple times, particularly the purging steps are carried out before back pressure after aerobic propulsion, acid gas adhered to the inner wall of the reaction chamber is reduced, pollution of the acid gas to the reaction chamber is reduced, and the sheet resistance uniformity, the passivation effect, the cell electrical performance parameters and the yield are improved.

Description

A kind of boron diffusion reaction system and process method thereof

technical field

The invention relates to a boron diffusion device for semiconductors or solar cells and the technical field thereof, and belongs to the technical field of solar cell production and manufacture.

Background technique

TOPCon cell is one of the next generation of crystalline silicon solar cell products with market prospects, because the heterojunction (PN junction) in the crystalline silicon cell material will affect the band gap, conductivity type, dielectric constant, refractive index and absorption coefficient, etc. Therefore, the preparation of PN junctions in the manufacturing process of crystalline silicon battery materials is particularly critical. The PN junction is the core of the solar cell. The PN junction of the N-type cell forms a P-type emitter on the surface of the original N-type silicon substrate through high temperature diffusion, ion implantation, laser doping, chemical vapor deposition, etc. The high temperature diffusion process is the main PN junction formation step. However, it is relatively difficult to control the ECV curve of doping concentration and depth. Boron atoms are easy to aggregate to the (surface) oxide layer during diffusion, resulting in uneven diffusion and affecting the passivation effect, ultimately resulting in battery electrical performance parameters and yield. poor. The main reason for the uneven diffusion is that the diffusion distribution of each reaction gas in the diffusion process is inconsistent. Therefore, improving the gas supply system of the boron diffusion equipment will be an important part of improving the electrical performance parameters and yield of the battery.

SUMMARY OF THE INVENTION

The object of the present invention is to provide a boron diffusion reaction system and a process method thereof for at least one technical problem in the above background technology, so as to further improve the uniformity of the square resistance of the boron diffusion process, the passivation effect, the battery electrical performance parameters and the Yield.

The scheme provided by the invention is as follows:

A boron diffusion reaction system includes a reaction furnace tube and a gas supply system, wherein the gas supply system includes an intake pipeline, an exhaust pipeline and a raw material pipeline; the raw material pipeline is connected with the intake pipeline, and the gas supply pipeline is connected to the reaction pipe through the intake pipeline. The raw gas is transported in the furnace tube;

The gas extraction pipe is arranged at the furnace tail of the reaction furnace tube, and the gas extraction pipe is located at the position of the tube axis of the reaction furnace tube;

The air intake line includes a first air intake line and a second air intake line, the air outlets of the first air intake line and the second air intake line are located at the furnace mouth, and the first air intake line and the second air intake line are located at the furnace mouth. The air outlets of the air inlet pipeline are symmetrically distributed up and down in the mid-plane in the vertical direction of the reaction furnace tube.

As a preference of the above technical solution, the air inlet pipeline extends from the furnace tail to the furnace mouth of the reaction furnace tube inside the reaction furnace tube.

As a preference of the above technical solution, the raw material pipeline includes a first nitrogen pipeline, a boron source pipeline and an oxygen pipeline;

The first nitrogen pipeline includes a water vapor pipeline and a furnace door nitrogen filling pipeline; the furnace door nitrogen filling pipeline is connected with the furnace door air inlet on the furnace door of the reaction furnace tube, and the furnace door air inlet is located at the furnace door. The position of the tube axis of the reaction furnace tube; the water vapor pipeline, the boron source pipeline and the oxygen pipeline are confluent and then connected to the intake pipeline;

The water vapor pipeline is connected to the constant temperature water tank through the bubbling principle and then connected to the confluence.

As a preferred option of the above technical solution, the first nitrogen pipeline further includes a cleaning pipeline, one end of the cleaning pipeline is connected to the boron source pipeline, and is located before the one-way valve of the boron source pipeline.

As a preference of the above technical solution, the raw material pipeline further includes a second nitrogen pipeline, and the second nitrogen pipeline includes a process nitrogen pipeline for providing a nitrogen atmosphere for the boron doping reaction, and for regulating the internal pressure of the reaction furnace tube. The back pressure nitrogen filling pipeline and the tail gas treatment nitrogen pipeline that guides the exhaust gas discharged from the reactor tube;

The process nitrogen pipeline and the back pressure nitrogen filling pipeline are joined with the water vapor pipeline, the boron source pipeline and the oxygen pipeline and then connected to the intake pipeline.

As a preference of the above technical solution, the oxygen pipeline includes a large oxygen pipeline and a small oxygen pipeline connected in parallel.

As a preference of the above technical solution, a tail gas treatment device is connected behind the exhaust pipe, and the tail gas treatment device includes a condensing device, a filter device and a corrosion-resistant diaphragm pump connected in sequence along the gas movement direction; the exhaust gas treatment nitrogen pipeline is connected to The exhaust gas outlet of the tail gas treatment device is connected to each other, and is used to provide the tail gas with nitrogen for mixing and then evacuating or entering the subsequent process.

As a preference of the above technical solution, each of the first nitrogen pipeline, the boron source pipeline, the oxygen pipeline and the second nitrogen pipeline is sequentially connected with a filter, a pressure reducing valve, a pressure reducing valve and a pressure reducing valve according to the direction of airflow. meter, manual ball valve, mass flow meter and pneumatic diaphragm valve, the pneumatic diaphragm valve is connected before the one-way valve;

One end of the cleaning pipeline connected to the boron source pipeline is located between the manual ball valve and the mass flow meter.

As a preferred option of the above technical solution, the outside of the boron source pipeline is wrapped with a heating component.

Based on the same technical concept, the present invention also provides a process method for boron diffusion using the above boron diffusion reaction system, comprising the following steps:

Step S1 into the boat: put the textured silicon wafer into the constant temperature zone of the reaction furnace tube of the boron diffusion reaction system, and close the furnace door;

Step S2 temperature rise and leak detection: start the external heating device of the reaction furnace tube to raise the temperature in the reaction furnace tube of the boron diffusion reaction system to the set value, open the process nitrogen pipeline to fill the reaction furnace tube with nitrogen, and start the corrosion-resistant diaphragm pump to drive the pumping. The gas pipe reduces the pressure in the reaction furnace tube to the set value, and at the same time detects whether there is gas leakage in the furnace;

Oxygen before step S3: open the oxygen pipeline to supply oxygen to the reaction furnace tube, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to keep the pressure and temperature setting values unchanged, and form an oxide layer on the surface of the silicon wafer SiO ₂ ;

Step S4 deposition: open the oxygen pipeline, the boron source pipeline and the water vapor pipeline at the same time to introduce oxygen, boron source and nitrogen with water vapor, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to maintain the pressure and The temperature setting value remains unchanged, and the deposition doping is performed;

Step S5 anaerobic propulsion: after the deposition is completed, the oxygen pipeline is closed, the corrosion-resistant diaphragm pump is adjusted to keep the pressure and temperature setting values unchanged, and the first propulsion is carried out without introducing oxygen;

Step S6 aerobic propulsion: open the oxygen pipeline to supply oxygen to the reaction furnace tube, adjust the corrosion-resistant diaphragm pump to keep the pressure set value unchanged, adjust the external heating device of the reaction furnace tube to increase the temperature set value to the set value , the second propulsion is carried out in an oxygen environment;

Step S7 Back pressure: close the corrosion-resistant diaphragm pump, the oxygen pipeline, the boron source pipeline, the water vapor pipeline and the process nitrogen pipeline, open the back pressure nitrogen filling pipeline and introduce a large amount of nitrogen to make the reaction furnace tube return to normal pressure state;

Step S8, get out of the boat: open the furnace door, take the doped silicon wafer out of the reaction furnace tube of the boron diffusion reaction system and put it into the cooling zone, and close the furnace door.

As a preference of the above technical solution, the number of times of deposition in the step S4 is 1-10 times; there are purging steps before and after each deposition step, and each purging after the deposition step is purging while heating up; In step S7, there is also a purging step before the furnace door is opened by back pressure; the purging step refers to stopping feeding the boron source into the boron source pipeline, and then feeding nitrogen into the boron source pipeline and the reaction furnace tube through the cleaning pipeline. Purge.

As the optimization of the above-mentioned technical scheme, the process method that the above-mentioned boron diffusion reaction system is used to complete comprises the following specific steps:

Step S1 into the boat: put the textured silicon wafer into the constant temperature zone of the reaction furnace tube of the boron diffusion reaction system, and close the furnace door;

Step S2 temperature rise and leak detection: start the external heating device of the reaction furnace tube to raise the temperature in the reaction furnace tube of the boron diffusion reaction system to 750°C-850°C, open the process nitrogen pipeline to fill the reaction furnace tube with nitrogen and start the corrosion-resistant diaphragm pump Drive the exhaust pipe to reduce the pressure in the reaction furnace tube to 150-250mbar, and at the same time detect whether there is air leakage in the furnace;

Oxygen before step S3: open the oxygen pipeline to supply oxygen 1000-3000sccm to the reaction furnace tube, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to keep the pressure and temperature set values unchanged, and form a surface of the silicon wafer. Layer oxide layer SiO ₂ , time 300-1000s;

Step S4 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, keep the pressure and temperature set values unchanged, and pass Purge nitrogen 200-1000sccm to purge the reactor tube and boron source pipeline for 100-300s;

Step S5 Deposition 1: Open the oxygen pipeline, the boron source pipeline and the water vapor pipeline at the same time to introduce oxygen 200-1000 sccm, boron source 50-500 sccm and nitrogen with water vapor, and adjust the corrosion-resistant diaphragm pump and reaction furnace tube The external heating device is used to keep the pressure and temperature settings unchanged, and the deposition and doping are carried out, and the time is 50-300s;

Step S6 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, keeping the pressure set value unchanged and the temperature set value unchanged Raise the temperature to 850°C-950°C, and at the same time, pour 200-1000sccm of cleaning nitrogen to purge the reaction furnace tube and the boron source pipeline, and the time is 100-300s;

Step S7 Deposition 2: Open the oxygen pipeline, the boron source pipeline and the water vapor pipeline at the same time to introduce oxygen 200-1000 sccm, boron source 50-500 sccm and nitrogen with water vapor, and adjust the corrosion-resistant diaphragm pump and reaction furnace tube The external heating device is used to keep the pressure and temperature settings unchanged, and the deposition and doping are carried out, and the time is 100-500s;

Step S8 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, and adjust the pressure to 400-800mbar and the temperature setting to increase. Up to 950℃-1050℃, purge the reaction furnace tube and boron source pipeline with purging nitrogen gas for 200-1000sccm, the time is 100-300s;

Step S9 anaerobic propulsion: after the purging is completed, continue to feed the boron source into the boron source pipeline and close the oxygen pipeline, adjust the corrosion-resistant diaphragm pump to keep the pressure and temperature set values unchanged, and carry out in an environment without oxygen. The first push, time 800-1500s;

Step S10 Aerobic propulsion: open the oxygen pipeline for the reaction furnace tube to introduce oxygen at 9000-18000 sccm, adjust the corrosion-resistant diaphragm pump to keep the pressure set value unchanged, and adjust the external heating device of the reaction furnace tube to increase the temperature set value to 1050℃-1200℃, the second propulsion is carried out in the oxygen environment, the time is 1500-5000s;

Step S11 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, keep the temperature set value unchanged, and reduce the pressure set The value is 150-250mbar, and a large amount of nitrogen 5000-20000sccm is introduced to purge the reaction furnace tube and the boron source pipeline, and the time is 200-500s;

Step S12 Back pressure: set the pressure value as normal pressure 1000-1100mbar, close the corrosion-resistant diaphragm pump, close the corrosion-resistant diaphragm pump, oxygen pipeline, boron source pipeline, water vapor pipeline and process nitrogen pipeline, and open the back pressure Pour a large amount of nitrogen into the nitrogen filling pipeline to make the reaction furnace tube return to the normal pressure state, and the time is 50-100s;

Step S13, get out of the boat: open the furnace door, take out the doped silicon wafer boron diffusion reaction system reaction furnace tube into the cooling zone, and close the furnace door.

Compared with the prior art, the beneficial effects of the present invention are:

(1) The intake pipe of the gas supply system extends from the furnace tail to the furnace mouth inside the reaction furnace tube, and the exhaust pipe is arranged on the furnace tail side. An air intake line and a second air intake line; the furnace mouth adopts multi-pipe air intake and cooperates with the exhaust pipe at the tail side of the furnace, so that the furnace mouth end of the reaction furnace tube forms a state of uniform diffusion and full gas in a short time after the air intake , to ensure the overall diffusion uniformity in the reactor tube. The air intake pipe extends from the furnace tail to the furnace mouth, so that the incoming gas has a heating section in the furnace, which ensures the temperature consistency of the incoming gas; the air intake pipeline is close to the furnace mouth and cooperates with the exhaust pipe at the furnace end to guide the reaction. The gas in the furnace tube flows from the furnace mouth side to the furnace tail side, which further reduces the flow of acid gas in the reaction furnace tube to the furnace door area, reduces the corrosion probability of the furnace door, and makes the diffusion gas have a uniform diffusion stage; When there are two air inlet pipes, the atmosphere field in the reaction furnace tube is symmetrically distributed, which further improves the uniformity of the gas flow field in the reaction furnace tube, thereby improving the uniformity within the diffusion square and the uniformity between the sheets, and ensuring the passivation effect.

(2) The nitrogen filling pipeline of the furnace door is connected to the air inlet of the furnace door, and nitrogen is supplied to the reaction furnace tube through the annular air passage on the stainless steel furnace door, so that the cavity between the inner quartz furnace door and the stainless steel furnace door forms a slightly positive It can prevent the residual acid gas in the reaction furnace tube from flowing to the stainless steel furnace door and cause corrosion, reduce the metal ion pollution in the reaction furnace tube, and further improve the passivation effect of the boron doping process, the electrical performance parameters and yield of the cell.

(3) Nitrogen, oxygen and boron source gases are combined before entering the reaction furnace tube, and the first gas supply pipeline and the second gas supply pipeline are set to extend from the furnace tail side to the furnace mouth side, which is equivalent to adding nitrogen , oxygen, and boron source gas to fully mix the three gases, so that the reaction gas mixing is more uniform, thereby improving the uniformity of doping. Each branch before the gas supply pipeline enters the reaction furnace tube is provided with a one-way valve to prevent the residual gas in the reaction furnace tube from flowing back to the gas supply pipeline to cause pollution when the reaction furnace tube returns to the normal pressure state.

(4) The outside of the boron source pipeline is wrapped with a heating part to prevent the liquefaction of boron source gas such as boron trichloride to produce powder that blocks the pipeline or the mass flowmeter on the boron source pipeline; the cleaning pipeline is wrapped with a heating part to prevent gas from entering The temperature is too low to liquefy the residual boron trichloride gas.

(5) The gas supply system of the present invention is combined with the process method, by optimizing the connection and coordination of the boron source pipeline and other gas pipelines and optimizing the sequence of process steps, optimizing process parameters such as pressure, temperature and processing time in each step; The passivation effect is better. Through multiple purging steps, especially a purging step before back pressure after aerobic propulsion, the pressure is reduced again after the aerobic step at a higher pressure, and the residual gas is further evacuated to reduce the acid gas adhering to the inner wall of the reaction chamber, reducing the The contamination of the reaction chamber by the acid gas can further improve the passivation effect of the boron doping process, the electrical performance parameters and the yield of the cell. In the aerobic propulsion step, nitrogen gas carries water vapor into the reaction furnace tube through the bubbling principle, which can speed up the reaction rate of the oxidation step, and further improve the productivity of the boron diffusion reaction system and the quality of boron doping.

Description of drawings

FIG. 1 shows a schematic diagram of piping connections of the boron diffusion reaction system of the present invention.

Legend description: 100, the first nitrogen pipeline; 101, the water vapor pipeline; 102, the furnace door nitrogen filling pipeline; 103, the cleaning pipeline; 200, the boron source pipeline; 300, the oxygen pipeline; 301, the large oxygen pipeline pipeline; 302, small oxygen pipeline; 400, second nitrogen pipeline; 401, process nitrogen pipeline; 402, back pressure nitrogen filling pipeline; 403, exhaust gas treatment nitrogen pipeline;

1. Filter; 2. Pressure reducing valve; 3. Pressure gauge; 4. Manual ball valve; 5. Mass flow meter; 6. Pneumatic diaphragm valve; 7. Constant temperature water tank; 8. One-way valve; 9. Air extraction pipe; 10 11, the first air inlet pipeline; 12, the second air inlet pipeline; 13, the furnace door air inlet; 14, the condensing device; 15, the filter device; 16, the corrosion-resistant diaphragm pump.

Detailed ways

In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and in detail below, but the protection scope of the present invention is not limited to the following specific examples.

Unless otherwise defined, all technical terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments, and are not intended to limit the protection scope of the present invention.

Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or can be prepared by existing methods.

Example 1

As shown in FIG. 1 , a boron diffusion reaction system includes a reaction furnace tube 10 and a gas supply system. The gas supply system includes an intake pipeline, an exhaust pipe 9 and a raw material pipeline; the raw material pipeline and the intake pipeline are connected, and the raw material gas is transported into the reaction furnace tube 10 through the air inlet pipeline;

The gas extraction pipe 9 is arranged at the furnace tail of the reaction furnace tube 10, and the gas extraction pipe 9 is located at the tube axis position of the reaction furnace tube 10;

The air intake line includes a first air intake line 11 and a second air intake line 12, the air outlets of the first air intake line 11 and the second air intake line 12 are located at the furnace mouth, and the first air intake pipe The gas outlets of the passage 11 and the second gas inlet pipeline 12 are symmetrically distributed up and down in the vertical mid-plane of the reaction furnace tube 10 .

In this embodiment, the air inlet pipeline extends from the furnace tail to the furnace mouth of the reaction furnace tube 10 inside the reaction furnace tube 10 .

In this embodiment, the raw material pipeline includes a first nitrogen pipeline 100, a boron source pipeline 200 and an oxygen pipeline 300;

The first nitrogen gas pipeline 100 includes a water vapor pipeline 101 and a furnace door nitrogen charging pipeline 102; the furnace door nitrogen charging pipeline 102 is connected to the furnace door air inlet 13 on the furnace door of the reaction furnace tube 10. The furnace door air inlet 13 is located at the tube axis position of the reaction furnace tube 10; the water vapor pipeline 101 is connected to the air intake pipeline after confluence with the boron source pipeline 200 and the oxygen pipeline 300;

The water vapor pipeline 101 is connected to the constant temperature water tank 7 and then connected to the junction.

In this embodiment, the first nitrogen pipeline 100 further includes a cleaning pipeline 103 , and one end of the cleaning pipeline 103 is connected to the boron source pipeline 200 and is located at the end of the boron source pipeline 200 . Before check valve 8.

In this embodiment, the raw material pipeline further includes a second nitrogen pipeline 400, and the second nitrogen pipeline 400 includes a process nitrogen pipeline 401 for providing nitrogen atmosphere for the boron doping reaction, and for regulating the reaction furnace tube. 10 The back pressure nitrogen filling pipeline 402 of the internal air pressure and the exhaust gas treatment nitrogen pipeline 403 for guiding the exhaust gas discharged from the reaction furnace tube 10;

The process nitrogen pipeline 401 and the back pressure nitrogen filling pipeline 402 are joined with the water vapor pipeline 101 , the boron source pipeline 200 and the oxygen pipeline 300 and then connected to the intake pipeline.

In this embodiment, the oxygen pipeline 300 includes a large oxygen pipeline 301 and a small oxygen pipeline 302 connected in parallel.

The large oxygen pipeline 301 and the small oxygen pipeline 302 can provide oxygen in two different flow ranges according to process requirements. The process nitrogen line 401 provides a low-pressure gas atmosphere for the reaction furnace tube 10 to maintain a low-pressure state. The back pressure nitrogen charging pipeline 402 is mainly for quickly charging a large amount of nitrogen before opening the furnace door to make the pressure of the reaction furnace tube 10 return to the normal pressure state. The exhaust gas treatment nitrogen pipeline 403 manually controls the flow rate through a needle valve, and is connected to the rear end of the filter device for cleaning and purging the corrosion-resistant diaphragm pump 16 .

In this embodiment, an exhaust gas treatment device is connected behind the exhaust pipe 9, and the exhaust gas treatment device includes a condensing device 14, a filter device 15 and a corrosion-resistant diaphragm pump 16 connected in sequence along the gas movement direction; the exhaust gas treats nitrogen gas The pipeline 403 is connected with the gas outlet of the tail gas treatment device, and is used to provide the tail gas with nitrogen for mixing and then evacuating or entering the subsequent process.

In this embodiment, each of the first nitrogen pipeline 100 , the boron source pipeline 200 , the oxygen pipeline 300 and the second nitrogen pipeline 400 is sequentially connected with the filter 1 , the reducing pressure valve 2, pressure gauge 3, manual ball valve 4, mass flow meter 5 and pneumatic diaphragm valve 6, the pneumatic diaphragm valve 6 is connected before the one-way valve 8;

One end of the cleaning pipeline 103 connected to the boron source pipeline 200 is located between the manual ball valve 4 and the mass flow meter 5 .

The filter 1 is used to filter the impurities in the peripheral intake pipe, the pressure reducing valve 2 can adjust the pressure value of the peripheral intake pipe within a certain range, and the pressure gauge 3 can digitally display the gas supply pressure value of the process gas branch. The manual ball valve 4 can manually open or close the air supply, the mass flow meter 5 can adjust the air supply flow rate, and the pneumatic diaphragm valve 6 can automatically open or close the air supply under certain conditions with the electrical system.

In this embodiment, the outside of the boron source pipeline 200 is wrapped with a heating component.

Example 2

Adopt the boron diffusion reaction system in the embodiment 1 to carry out the processing method of boron diffusion, comprises the following steps:

Step S1 into the boat: put the textured silicon wafer into the constant temperature zone of the reaction furnace tube of the boron diffusion reaction system, and close the furnace door;

Step S2 temperature rise and leak detection: start the external heating device of the reaction furnace tube to raise the temperature in the reaction furnace tube of the boron diffusion reaction system to 810°C, open the process nitrogen pipeline to fill the reaction furnace tube with nitrogen, and start the corrosion-resistant diaphragm pump to drive the gas extraction pipe Reduce the pressure in the reaction furnace tube to 230mbar, and check whether there is air leakage in the furnace at the same time, the time is 720s;

Oxygen before step S3: open the oxygen pipeline to feed 2000sccm of oxygen into the reaction furnace tube, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to keep the pressure and temperature set values unchanged, and form a layer of oxide on the surface of the silicon wafer Layer SiO ₂ , time 300s;

Step S4 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, keep the pressure and temperature set values unchanged, and pass Purge nitrogen 3000sccm to purge the reaction furnace tube and boron source pipeline for 230s;

Step S5 Deposition 1: Open the oxygen pipeline, the boron source pipeline and the water vapor pipeline at the same time to introduce oxygen 360 sccm, boron source 120 sccm and nitrogen with water vapor, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to Keep the pressure and temperature set values unchanged, carry out deposition doping, the time is 120s;

Step S6 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, keeping the pressure set value unchanged and the temperature set value unchanged Raise the temperature to 850°C, and at the same time, purge the reaction furnace tube and the boron source pipeline with 300sccm of cleaning nitrogen for 300s;

Step S7 Deposition 2: Open the oxygen pipeline, the boron source pipeline and the water vapor pipeline at the same time to introduce oxygen 360 sccm, boron source 120 sccm and nitrogen with water vapor, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to Keep the pressure and temperature set values unchanged, carry out deposition doping, the time is 240s;

Step S8 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, and adjust the pressure to 800mbar and the temperature set value to 800 mbar. 950℃, purge the reaction furnace tube and boron source pipeline with purging nitrogen for 300sccm for 300s;

Step S9 anaerobic propulsion: after the purging is completed, continue to feed the boron source into the boron source pipeline and close the oxygen pipeline, adjust the corrosion-resistant diaphragm pump to keep the pressure and temperature set values unchanged, and carry out in an environment without oxygen. The first push, time 900s;

Step S10 aerobic propulsion: open the oxygen pipeline to supply oxygen to the reaction furnace tube, introduce nitrogen flow rate of 1000sccm, oxygen flow rate of 10000sccm, purge nitrogen flow rate of 300sccm, adjust the corrosion-resistant diaphragm pump to keep the pressure set value unchanged, adjust the reaction furnace The external heating device of the tube increases the temperature set value to 1050℃, and carries out the second push in the oxygen environment for 4200s;

Step S11 purging: stop feeding the boron source to the boron source pipeline, and then feed nitrogen through the cleaning pipeline to the boron source pipeline and the reaction furnace tube for purging, lower the temperature to 780°C, and reduce the pressure setting to 200mbar , Purge a large amount of nitrogen 50000sccm to purge the reaction furnace tube and boron source pipeline for 360s;

Step S12 Back pressure: set the pressure value as normal pressure 1000mbar, temperature 780℃; close the corrosion-resistant diaphragm pump, close the corrosion-resistant diaphragm pump, oxygen pipeline, boron source pipeline, water vapor pipeline and process nitrogen pipeline, open A large amount of nitrogen is introduced into the back pressure nitrogen filling pipeline to make the reaction furnace tube return to the normal pressure state, and the time is 70s;

Step S13, get out of the boat: open the furnace door, take out the doped silicon wafer boron diffusion reaction system reaction furnace tube into the cooling zone, and close the furnace door.

The parameter indexes obtained by the conventional process method, the supply gas of the present invention and the inventive process are shown in the following table, the process time, the uniformity of the square resistance within the chip, the uniformity of the square resistance between the chips, the open circuit voltage, the short circuit current, the filling factor of the inventive process , efficiency and other indicators are higher than the conventional process of the existing battery production line.

It should be noted that the above-mentioned embodiments are only used to explain the present invention, and do not constitute any limitation to the present invention. The present invention has been described with reference to typical embodiments, but it is to be understood that the words used therein are words of description and explanation, rather than words of limitation. The present invention may be modified within the scope of the claims of the present invention as specified, and may be modified without departing from the scope and spirit of the present invention. The above are only preferred embodiments of the present invention, and the protection scope of the present invention is not limited to the above embodiments. For those skilled in the art, improvements and transformations obtained without departing from the technical concept of the present invention should also be regarded as the protection scope of the present invention.

Claims (10)

1. A boron diffusion reaction system, comprising a reaction furnace tube (10) and a gas supply system, wherein the gas supply system comprises an air intake line, an air extraction pipe (9) and a raw material pipeline; the raw material pipeline It is connected with the intake pipeline, and the raw material gas is transported into the reaction furnace tube (10) through the intake pipeline; The gas extraction pipe (9) is arranged at the furnace tail of the reaction furnace pipe (10), and the gas extraction pipe (9) is located at the position of the pipe axis of the reaction furnace pipe (10); The air intake pipeline includes a first air intake pipeline (11) and a second air intake pipeline (12), and the air outlets of the first air intake pipeline (11) and the second air intake pipeline (12) are located at the furnace mouth , and the air outlets of the first air inlet pipe (11) and the second air inlet pipe (12) are symmetrically distributed up and down in the vertical mid-plane of the reaction furnace tube (10). 2 . The boron diffusion reaction system according to claim 1 , wherein the air inlet pipeline extends from the furnace tail to the furnace mouth of the reaction furnace tube ( 10 ) inside the reaction furnace tube ( 10 ). 3 . place. 3. The boron diffusion reaction system according to claim 1, wherein the raw material pipeline comprises a first nitrogen pipeline (100), a boron source pipeline (200) and an oxygen pipeline (300); The first nitrogen pipeline (100) includes a water vapor pipeline (101) and a furnace door nitrogen charging pipeline (102); the furnace door nitrogen charging pipeline (102) and the reaction furnace tube (10) on the furnace door The door air inlet (13) is connected, and the furnace door air inlet (13) is located at the tube axis position of the reaction furnace tube (10); the water vapor pipeline (101) is connected to the boron source pipeline (200). ), the oxygen pipeline (300) is connected to the intake pipeline after confluence; The water vapor pipeline (101) is connected to the constant temperature water tank (7) and then connected to the junction. 4. The boron diffusion reaction system according to claim 3, wherein the first nitrogen gas pipeline (100) further comprises a cleaning pipeline (103), and one end of the cleaning pipeline (103) is connected to the on the boron source pipeline (200) and before the one-way valve (8) of the boron source pipeline (200). 5 . The boron diffusion reaction system according to claim 4 , wherein the raw material pipeline further comprises a second nitrogen pipeline ( 400 ), and the second nitrogen pipeline ( 400 ) comprises a boron doping reaction system. 6 . A process nitrogen pipeline (401) for providing nitrogen atmosphere, a back pressure nitrogen filling pipeline (402) for regulating the internal pressure of the reaction furnace tube (10), and a tail gas treatment nitrogen pipeline for guiding the exhaust gas in the reaction furnace tube (10) to be discharged (403); The process nitrogen pipeline (401) and the back pressure nitrogen filling pipeline (402) are combined with the water vapor pipeline (101), the boron source pipeline (200) and the oxygen pipeline (300), and then merge with the Intake line connection. 6 . The boron diffusion reaction system according to claim 5 , wherein a tail gas treatment device is connected behind the exhaust pipe ( 9 ), and the tail gas treatment device comprises a condensing device ( 14 ) sequentially connected along the gas movement direction. 7 . , a filter device (15) and a corrosion-resistant diaphragm pump (16); the exhaust gas treatment nitrogen pipeline (403) is connected to the outlet of the exhaust gas treatment device, and is used to provide the exhaust gas with nitrogen to mix and then empty or enter the subsequent craft. 7. The boron diffusion reaction system according to claim 5, wherein the first nitrogen pipeline (100), the boron source pipeline (200), the oxygen pipeline (300) and the second nitrogen pipeline ( 400) are sequentially connected with a filter (1), a pressure reducing valve (2), a pressure gauge (3), a manual ball valve (4), a mass flowmeter (5) and a pneumatic diaphragm valve according to the direction of airflow. (6), before the pneumatic diaphragm valve (6) is connected to the one-way valve (8); One end of the cleaning pipeline (103) connected to the boron source pipeline (200) is located between the manual ball valve (4) and the mass flow meter (5). 8. The boron diffusion reaction system according to claim 3, characterized in that, the outside of the boron source pipeline (200) is wrapped with a heating component. 9. A process method for carrying out boron diffusion using the boron diffusion reaction system according to any one of claims 1-8, characterized in that, comprising the following steps: Step S1 into the boat: put the textured silicon wafer into the constant temperature zone of the reaction furnace tube of the boron diffusion reaction system, and close the furnace door; Step S2 temperature rise and leak detection: start the external heating device of the reaction furnace tube to raise the temperature in the reaction furnace tube of the boron diffusion reaction system to the set value, open the process nitrogen pipeline to fill the reaction furnace tube with nitrogen, and start the corrosion-resistant diaphragm pump to drive the pumping. The gas pipe reduces the pressure in the reaction furnace tube to the set value, and at the same time detects whether there is gas leakage in the furnace; Oxygen before step S3: open the oxygen pipeline to supply oxygen to the reaction furnace tube, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to keep the pressure and temperature setting values unchanged, and form an oxide layer on the surface of the silicon wafer SiO ₂ ; Step S4 deposition: open the oxygen pipeline, the boron source pipeline and the water vapor pipeline at the same time to introduce oxygen, boron source and nitrogen with water vapor, adjust the corrosion-resistant diaphragm pump and the external heating device of the reaction furnace tube to maintain the pressure and The temperature setting value remains unchanged, and the deposition doping is performed; Step S5 anaerobic propulsion: after the deposition is completed, the oxygen pipeline is closed, the corrosion-resistant diaphragm pump is adjusted to keep the pressure and temperature setting values unchanged, and the first propulsion is carried out without introducing oxygen; Step S6 aerobic propulsion: open the oxygen pipeline to supply oxygen to the reaction furnace tube, adjust the corrosion-resistant diaphragm pump to keep the pressure set value unchanged, adjust the external heating device of the reaction furnace tube to increase the temperature set value to the set value , the second propulsion is carried out in an oxygen environment; Step S7 Back pressure: close the corrosion-resistant diaphragm pump, the oxygen pipeline, the boron source pipeline, the water vapor pipeline and the process nitrogen pipeline, open the back pressure nitrogen filling pipeline and introduce a large amount of nitrogen to make the reaction furnace tube return to normal pressure state; Step S8, get out of the boat: open the furnace door, take the doped silicon wafer out of the reaction furnace tube of the boron diffusion reaction system and put it into the cooling zone, and close the furnace door. 10. The process method according to claim 9, wherein the deposition times of the step S4 are 1-10 times; there are purging steps before and after each deposition step, and each purging after the deposition step is at Purging is carried out while heating up; there is also a purging step before the furnace door is opened by back pressure in step S7; the purging step refers to stopping the feeding of the boron source to the boron source pipeline, and then to the boron source pipeline through the cleaning pipeline. The pipeline and the reactor tube are sent into nitrogen for purging.

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